1. Field of the Invention
The present invention relates to a control apparatus for a hydraulically operated vehicular transmission having a plurality of speed stages to be established by a selective operation of a plurality of hydraulic engaging elements. In this specification, the term "vehicular transmission" means a transmission for a vehicle such as a motor vehicle.
2. Description of the Related Art
In this kind of apparatus, there are conventionally provided a vehicle speed detecting means for detecting the vehicle speed, and a speed stage determining means for determining the speed stage to be established in the forward range or position (or forward running range or position) depending on the vehicle speed, to thereby perform speed changing in the forward range. In concrete, there is prepared a speed change map in which is set the relationship between the vehicle speed and the speed stage. A speed stage to be established is thus determined from the speed change map by using the detected vehicle speed as a parameter.
The means for detecting the vehicle speed detects only the rotational speed of a wheel and does not detect the direction of rotation thereof. Therefore, also when a switching is made to the forward range while the vehicle is running at a high speed in the reverse range, a judgement is made that the vehicle is running at a high speed, thereby establishing a high speed stage. In this case, the switching is made from the reverse running to the forward running by a torque transmission via a high speed stage. However, since the transmitted torque to the driving wheels becomes small in the high speed stage, it takes time to switch from the reverse running to the forward running. During this period of time, the hydraulic engaging element keeps on slipping, with the result that the durability of the hydraulic engaging element is deteriorated.
In view of the above point, the present invention has an object of providing a control apparatus in which, when a switch is made to a forward range while running in the reverse direction, the switching to the forward running condition can be made at an early time to thereby prevent the hydraulic engaging element from deteriorating in durability.